Endoscope

ABSTRACT

An endoscope including an operation part having a forceps entrance, a distal end part having a flat end surface, an observation window base part formed on the flat end surface of the distal end part so as to protrude distally from the flat end surface, an observation window disposed on the observation window base part, and a forceps exit disposed on the distal end part, a forceps being inserted through a forceps entrance protruding from the forceps exit. The observation window base part has a flat surface, and an outer peripheral shape of the observation window base part is inclined and connects the flat end surface of the distal end part with the flat surface of the observation window base part.

The present application is a Continuation Application of U.S. patentapplication Ser. No. 14/093,446, filed on Nov. 30, 2013, which is aContinuation Application of U.S. patent application Ser. No. 13/158,230,filed Jun. 10, 2011, now U.S. Pat. No. 9,173,555, issued on Nov. 3,2015, which is based on and claims priority to Japanese PatentApplication No. 2010-134014, filed on Jun. 11, 2010, the entire contentsof which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The presently disclosed subject matter relates to an endoscope, and moreparticularly, to an endoscope in which an observation window can becleaned by jetting a cleaning fluid from a nozzle.

Description of the Related Art

There has been known an endoscope including a cleaning nozzle at adistal end part thereof, in which a cleaning liquid (such as water) anda gas (such as air and carbon dioxide gas) are jetted from the cleaningnozzle toward an observation window, to thereby enable cleaning of theobservation window.

Japanese Patent Application Laid-Open No. 03-165731 describes atechnology concerning such an endoscope including the cleaning nozzle,in which a convex portion is provided between the observation window andthe cleaning nozzle, to thereby distribute the cleaning liquid to allover the surface of the observation window.

In addition, Japanese Patent Application Laid-Open No. 2003-210388describes a technology in which the observation window is formed so asto protrude by a predetermined amount from an end surface of the distalend part, a peripheral edge of the observation window is formed so as tobe inclined, and the cleaning liquid is jetted from the cleaning nozzletoward the inclined peripheral edge of the observation window.

In addition, Japanese Patent Application Laid-Open Nos. 2006-314459,2006-320366, 2006-320367, and 2008-86664 each describe a technology inwhich the end surface of the distal end part on which the observationwindow is placed is formed in a stepwise manner, an inclined surface isformed in a wall part between respective adjacent two steps, and thecleaning liquid is jetted from the cleaning nozzle toward the inclinedsurfaces.

SUMMARY OF THE INVENTION

However, in the conventional structure of the distal end part, whenjetting of the cleaning liquid is stopped, liquid drops remain on theobservation window to block the field of view in some cases. That is,even after an operation of stopping the jetting is performed, thecleaning nozzle cannot stop discharging the cleaning liquid immediately,and instead the jetting gradually loses its force to stop. Therefore,the cleaning liquid which is discharged around the end and has weakforce cannot pass through the observation window to attach onto theobservation window in some cases. In addition, in the case whereswitching is made from water supply to air supply, the cleaning liquidremaining inside of a tube is pushed by the gas to be discharged fromthe cleaning nozzle. Similarly at this time, the cleaning liquid isdischarged from the cleaning nozzle without strong force, and thusattaches onto the observation window in some cases. The liquid dropsattaching on the observation window in this way are removed by jetting agas from the cleaning nozzle, and there is a disadvantage that apressure of the supplied gas needs to be made strong in order tocompletely remove minute liquid drops.

In addition, in recent years, a diameter of the endoscope becomesincreasingly smaller, which causes a situation where the observationwindow is placed in the vicinity of an outer peripheral edge of thedistal end part. Normally, the outer peripheral edge of the distal endpart is round-chamfered, and there are problems that the liquid dropseasily attach onto such a round-chamfered portion, and that it isdifficult to remove the liquid drops once attaching thereon.Accordingly, if the observation window is placed in the vicinity of theround-chamfered outer peripheral edge as described above, there is adisadvantage that the liquid drops remain on the observation window moreeasily.

The presently disclosed subject matter has been made in view of theabove-mentioned circumstances, and therefore has an object to provide anendoscope which is capable of letting a liquid drain off to asatisfactory level at the time of cleaning, while securing the degree offreedom of a layout.

In order to achieve the above-mentioned object, a first aspect of thepresently disclosed subject matter provides an endoscope including: adistal end part having a round-chamfered outer peripheral edge; anobservation window on an end surface of the distal end part; a nozzlewhich jets a cleaning fluid toward the observation window; and anobservation window base part on which the observation window is placed,the observation window which is formed on the end surface of the distalend part so as to protrude from a surrounding area, and has an outerperipheral shape formed into a streamline shape with respect to a flowof the cleaning fluid jetted from the nozzle.

According to the first aspect, the observation window is placed on theobservation window base part which is formed on the end surface of thedistal end part so as to protrude from the surrounding area. The outerperipheral shape of the observation window base part is formed into thestreamline shape with respect to the flow of the cleaning fluid jettedfrom the nozzle. With this feature, it is possible to block a liquidflow having a low flow rate from flowing on the observation window, andto allow the liquid flow which has been used for cleaning to promptlymove to the outside of the observation window.

In order to achieve the above-mentioned object, according to a secondaspect of the presently disclosed subject matter, in the endoscopeaccording to the first aspect, the observation window base part isformed so as to extend up to the outer peripheral edge of the distal endpart along the flow of the cleaning fluid jetted from the nozzle.

In the endoscope of the second aspect, the observation window base partis formed so as to extend up to the outer peripheral edge of the distalend part. With this feature, even in the case where the observationwindow is placed in the vicinity of the round-chamfered outer peripheralpart of the distal end part, it is possible to prevent liquid drops fromremaining on the observation window.

In order to achieve the above-mentioned object, a third aspect of thepresently disclosed subject matter provides an endoscope including: adistal end part having a round-chamfered outer peripheral edge; anobservation window on an end surface of the distal end part; a nozzlewhich jets a cleaning fluid toward the observation window; and anobservation window base part on which the observation window is placed,the observation window which is formed on the end surface of the distalend part so as to protrude from a surrounding area and to extend up toan outer peripheral edge of the distal end part along a flow of thecleaning fluid jetted from the nozzle.

According to the third aspect, the observation window is placed on theobservation window base part which is formed on the end surface of thedistal end part so as to protrude from the surrounding area. Theobservation window base part is formed so as to extend up to the outerperipheral edge of the distal end part along the flow of the cleaningfluid jetted from the nozzle. With this feature, even in the case wherethe observation window is placed in the vicinity of the round-chamferedouter peripheral part of the distal end part, it is possible to preventthe liquid drops from remaining on the observation window.

In order to achieve the above-mentioned object, a fourth aspect of thepresently disclosed subject matter provides an endoscope including: adistal end part having a round-chamfered outer peripheral edge; anobservation window on an end surface of the distal end part; a nozzlewhich jets a cleaning fluid toward the observation window; and anobservation window base part on which the observation window is placed,the observation window which is formed on the end surface of the distalend part so as to protrude from a surrounding area and to extend up toan outer peripheral edge of the distal end part along a straight linewhich connects the nozzle with the observation window.

According to the fourth aspect, the observation window is placed on theobservation window base part which is formed on the end surface of thedistal end part so as to protrude from the surrounding area. Theobservation window base part is formed so as to extend up to the outerperipheral edge of the distal end part along the straight line whichconnects the nozzle with the observation window. With this feature, evenin the case where the observation window is placed in the vicinity ofthe round-chamfered outer peripheral part of the distal end part, it ispossible to prevent the liquid drops from remaining on the observationwindow.

In order to achieve the above-mentioned object, a fifth aspect of thepresently disclosed subject matter provides an endoscope including: adistal end part having a round-chamfered outer peripheral edge; anobservation window on an end surface of the distal end part; a nozzlewhich jets a cleaning fluid toward the observation window; and anobservation window base part on which the observation window is placed,the observation window which is formed on the end surface of the distalend part so as to protrude from a surrounding area and to extend up toan outer peripheral edge of the distal end part located at a closestposition from the observation window.

According to the fifth aspect, the observation window is placed on theobservation window base part which is formed on the end surface of thedistal end part so as to protrude from the surrounding area. Theobservation window base part is formed so as to extend up to the outerperipheral edge located at the closest position from the observationwindow. With this feature, even in the case where the observation windowis placed in the vicinity of the round-chamfered outer peripheral partof the distal end part, it is possible to prevent the liquid drops fromremaining on the observation window.

In order to achieve the above-mentioned object, according to a sixthaspect of the presently disclosed subject matter, in the endoscopeaccording to any one of the third to fifth aspects, an outer peripheralshape of the observation window base part is formed so as to convergetoward the outer peripheral edge of the distal end part.

In the endoscope of the sixth aspect, the outer peripheral shape of theobservation window base part is formed so as to converge toward theouter peripheral edge of the distal end part. With this feature, it ispossible to allow the liquid flow which has been used for cleaning topromptly move to the outside of the observation window.

In order to achieve the above-mentioned object, according to a seventhaspect of the presently disclosed subject matter, in the endoscopeaccording to the sixth aspect, the outer peripheral shape of theobservation window base part is formed so as to converge toward thenozzle.

In the endoscope of the seventh aspect, the outer peripheral shape ofthe observation window base part is formed so as to converge toward thenozzle. With this feature, it is possible to block the liquid flowhaving a low flow rate from flowing on the observation window.

In order to achieve the above-mentioned object, according to an eighthaspect of the presently disclosed subject matter, in the endoscopeaccording to any one of the first to seventh aspects, an outerperipheral edge of the observation window base part is formed so as tobe inclined.

In the endoscope of the eighth aspect, the outer peripheral edge of theobservation window base part is formed so as to be inclined. With thisfeature, it is possible to more effectively block the liquid flow havinga low flow rate, and to allow the liquid flow which has been used forcleaning to promptly move to the outside of the observation window.

In order to achieve the above-mentioned object, according to a ninthaspect of the presently disclosed subject matter, the endoscopeaccording to any one of the first to eighth aspects further includes: anillumination window; and an illumination window base part on which theillumination window is placed, the illumination window which is formedon the end surface of the distal end part so as to protrude from asurrounding area, and has an outer peripheral shape formed into astreamline shape with respect to the flow of the cleaning fluid jettedfrom the nozzle.

According to the ninth aspect, the illumination window is placed on theillumination window base part which is formed on the end surface of thedistal end part so as to protrude from the surrounding area. The outerperipheral shape of the illumination window base part is formed into thestreamline shape with respect to the flow of the cleaning fluid jettedfrom the nozzle. With this feature, it is possible to block the liquidflow having a low flow rate from flowing on the illumination window, andto allow the liquid flow which has been used for cleaning to promptlymove to the outside of the illumination window.

In order to achieve the above-mentioned object, according to a tenthaspect of the presently disclosed subject matter, in the endoscopeaccording to the ninth aspect, the illumination window base part isformed so as to extend up to the outer peripheral edge of the distal endpart along the flow of the cleaning fluid jetted from the nozzle.

In the endoscope of the tenth aspect, the illumination window base partis formed so as to extend up to the outer peripheral edge of the distalend part. With this feature, even in the case where the illuminationwindow is placed in the vicinity of the round-chamfered outer peripheralpart of the distal end part, it is possible to prevent the liquid dropsfrom remaining on the illumination window.

In order to achieve the above-mentioned object, according to an eleventhaspect of the presently disclosed subject matter, the endo scopeaccording to any one of the first to eighth aspects further includes: anillumination window; and an illumination window base part on which theillumination window is placed, the illumination window which is formedon the end surface of the distal end part so as to protrude from asurrounding area and to extend up to an outer peripheral edge of thedistal end part along the flow of the cleaning fluid jetted from thenozzle.

In the endoscope of the eleventh aspect, the illumination window isplaced on the illumination window base part which is formed on the endsurface of the distal end part so as to protrude from the surroundingarea. The illumination window base part is formed so as to extend up tothe outer peripheral edge of the distal end part along the flow of thecleaning fluid jetted from the nozzle. With this feature, even in thecase where the illumination window is placed in the vicinity of theround-chamfered outer peripheral part of the distal end part, it ispossible to prevent the liquid drops from remaining on the illuminationwindow.

In order to achieve the above-mentioned object, according to a twelfthaspect of the presently disclosed subject matter, the endoscopeaccording to any one of the first to eighth aspects further includes: anillumination window; and an illumination window base part on which theillumination window is placed, the illumination window which is formedon the end surface of the distal end part so as to protrude from asurrounding area and to extend up to an outer peripheral edge of thedistal end part along a straight line which connects the nozzle with theillumination window.

In the endo scope of the twelfth aspect, the illumination window isplaced on the illumination window base part which is formed on the endsurface of the distal end part so as to protrude from the surroundingarea. The illumination window base part is formed so as to extend up tothe outer peripheral edge of the distal end part along the straight linewhich connects the nozzle with the illumination window. With thisfeature, even in the case where the illumination window is placed in thevicinity of the round-chamfered outer peripheral part of the distal endpart, it is possible to prevent the liquid drops from remaining on theillumination window.

In order to achieve the above-mentioned object, according to athirteenth aspect of the presently disclosed subject matter, the endoscope according to any one of the first to eighth aspects furtherincludes: an illumination window; and an illumination window base parton which the illumination window is placed, the illumination windowwhich is formed on the end surface of the distal end part so as toprotrude from a surrounding area and to extend up to an outer peripheraledge of the distal end part located at a closest position from theillumination window.

In the endo scope of the thirteenth aspect, the illumination window isplaced on the illumination window base part which is formed on the endsurface of the distal end part so as to protrude from the surroundingarea. The illumination window base part is formed so as to extend up tothe outer peripheral edge located at the closest position from theillumination window. With this feature, even in the case where theillumination window is placed in the vicinity of the round-chamferedouter peripheral part of the distal end part, it is possible to preventthe liquid drops from remaining on the illumination window.

In order to achieve the above-mentioned object, according to afourteenth aspect of the presently disclosed subject matter, in theendoscope according to any one of the ninth to thirteenth aspects, anouter peripheral shape of the illumination window base part is formed soas to converge toward the outer peripheral edge of the distal end part.

In the endoscope of the fourteenth aspect, the outer peripheral shape ofthe illumination window base part is formed so as to converge toward theouter peripheral edge of the distal end part. With this feature, it ispossible to allow the liquid flow which has been used for cleaning topromptly move to the outside of the illumination window.

In order to achieve the above-mentioned object, according to a fifteenthaspect of the presently disclosed subject matter, in the endoscopeaccording to the fourteenth aspect, the outer peripheral shape of theillumination window base part is formed so as to converge toward thenozzle.

In the endo scope of the fifteenth aspect, the outer peripheral shape ofthe illumination window base part is formed so as to converge toward thenozzle. With this feature, it is possible to block the liquid flowhaving a low flow rate from flowing on the illumination window.

In order to achieve the above-mentioned object, according to a sixteenthaspect of the presently disclosed subject matter, in the endoscopeaccording to any one of the ninth to fifteenth aspects, an outerperipheral edge of the illumination window base part is formed so as tobe inclined.

In the endo scope of the sixteenth aspect, the outer peripheral edge ofthe illumination window base part is formed so as to be inclined. Withthis feature, it is possible to more effectively block the liquid flowhaving a low flow rate, and to allow the liquid flow which has been usedfor cleaning to promptly move to the outside of the illumination window.

According to the presently disclosed subject matter, it is possible tolet a liquid drain off to a higher level at the time of cleaning, whilesecuring the degree of freedom of a layout when a diameter of theendoscope is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall configuration view illustrating an endoscope;

FIG. 2 is a front view illustrating a configuration of a distal endsurface of a distal end part;

FIG. 3A is an enlarged view illustrating a main part of FIG. 2, FIG. 3Bis a view taken in an arrow 3B direction of FIG. 3A, FIG. 3C is a viewtaken in an arrow 3C direction of FIG. 3A and FIG. 3D is a view taken inan arrow 3D direction of FIG. 3A;

FIG. 4A is an enlarged view illustrating a main part of FIG. 2, and FIG.4B is a view taken in an arrow 4B direction of FIG. 4A;

FIG. 5 is a front view illustrating a configuration of a secondembodiment of the distal end surface of the distal end part;

FIG. 6 is a front view illustrating a configuration of anotherembodiment of the distal end surface of the distal end part;

FIG. 7 is a front view illustrating a configuration of still anotherembodiment of the distal end surface of the distal end part;

FIG. 8 is a front view illustrating a configuration of a thirdembodiment of the distal end surface of the distal end part;

FIG. 9 is a front view illustrating a configuration of a fourthembodiment of the distal end surface of the distal end part;

FIG. 10 is a front view illustrating a configuration of anotherembodiment of the distal end surface of the distal end part;

FIG. 11 is a front view illustrating a configuration of a fifthembodiment of the distal end surface of the distal end part; and

FIG. 12 is a front view illustrating a configuration of anotherembodiment of the distal end surface of the distal end part.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of an endoscope according to thepresently disclosed subject matter are described in detail withreference to the attached drawings.

First Embodiment

FIG. 1 is an overall configuration view illustrating an embodiment ofthe endoscope according to the presently disclosed subject matter.

An endoscope 1 is an electronic endoscope which takes out a subjectimage inside of a body cavity as an electronic image, and includes: anoperation part 10 which is used by an operator in order to perform arequired operation; an insertion part 20 which is inserted into the bodycavity; and a connection part 30 for connecting with a processorapparatus and the like.

The connection part 30 includes: a universal code 32 which is providedso as to be continuous with the operation part 10; and a plurality ofconnectors which are provided at a distal end part of the universal code32. These connectors are configured by: a processor connector 34A forconnecting with a processor apparatus 36; a light source connector 34Bfor connecting with a light source apparatus 38; and an air supply/watersupply connector 34C for connecting with an air supply/water supplyapparatus 40.

The operation part 10 includes: a forceps entrance 12 for inserting atreatment tool; an angle knob 14 for bending a distal end of theinsertion part 20 up, down, right, or left; an air supply/water supplybutton 16 for cleaning an observation window 50 provided at the distalend of the insertion part 20, by jetting a cleaning liquid (such aswater) and a gas (such as air and carbon dioxide gas) from a nozzle 58provided at the distal end of the insertion part 20; and a suctionbutton 18 for suctioning from a forceps exit 56 provided at the distalend of the insertion part 20.

The insertion part 20 is formed into a tube-like shape which has aprescribed diameter and is circular in cross-section, and is integrallyprovided so as to be continuous with a distal end of the operation part10. The insertion part 20 includes: a flexible part 22 havingflexibility; a bendable bending part 24 provided at an end of theflexible part 22; and a distal end part 26 provided at a distal end ofthe bending part 24.

The flexible part 22 is made of a flexible tube, and is integrallyprovided so as to be continuous with the distal end of the operationpart 10. A large part of the insertion part 20 is configured by theflexible part 22.

The bending part 24 is configured to be bendable, and is integrallyprovided so as to be continuous with a distal end of the flexible part22. The bending part 24 bends up, down, right, or left so as to followan operation on the angle knob 14 provided in the operation part 10.Accordingly, the distal end part 26 can be turned in a desired directioninside of the body cavity by bending the bending part 24 in the desireddirection.

The distal end part 26 is formed into a columnar shape by using a hardmaterial such as metal (for example, stainless), and is integrallyprovided so as to be continuous with the distal end of the bending part24.

FIG. 2 is a front view illustrating a configuration of a distal endsurface of the distal end part. As illustrated in FIG. 2, a distal endsurface 26 a of the distal end part 26 included in the insertion part 20is formed into a circular shape, and the observation window 50, a pairof illumination windows 52 and 54, the forceps exit 56, and the nozzle58 are placed on the distal end surface 26 a. Particularly, in theendoscope 1 of the present embodiment, the observation window 50 isplaced at a position close to an outer periphery of the distal endsurface 26 a, and the pair of illumination windows 52 and 54 is placedat a position close to the outer periphery thereof so as to sandwich theobservation window 50. In addition, the nozzle 58 is placed so as to beopposed to the observation window 50, and the forceps exit 56 is placedadjacently to the nozzle 58. In addition, in the endoscope 1 of thepresent embodiment, an edge part 26 b of the outer periphery of thedistal end surface 26 a is round-chamfered uniformly at a prescribeddiameter (for example, a diameter of approximately 1.6 to 2.0 mm).

It should be noted that, although not illustrated, an objective opticalsystem such as an objective lens is attached behind the observationwindow 50, and a solid-state image pick-up element (for example, CCD(Charge Coupled Device)) is attached further behind the objectiveoptical system.

In addition, an illumination optical system is placed behind each of thepaired illumination windows 52 and 54.

A light guide (not shown) provided inside of the insertion part 20 isconnected to each illumination optical system. When the light sourceconnector 34B of the connection part 30 is connected to the light sourceapparatus 38, this light guide is connected to a light source lamp (notshown) incorporated in the light source apparatus 38. Accordingly, whenthe light source lamp of the light source apparatus 38 is turned on,light emitted from the light source lamp is guided by the light guide tothe illumination optical systems. Then, the lights guided by respectiveillumination optical systems illuminate a region to be observed throughthe illumination windows 52 and 54.

The objective optical system placed behind the observation window 50receives reflected light of the light which illuminates the region to beobserved through the illumination windows 52 and 54, and forms anoptical image of the region to be observed on a light receiving surfaceof the solid-state image pick-up element. The optical image of theregion to be observed which is formed on the light receiving surface ofthe solid-state image pick-up element is converted into an electricalsignal by the solid-state image pick-up element, and is outputted to theprocessor apparatus 36 which is connected to the endoscope 1 via asignal line (not shown) provided inside of the insertion part 20. Theprocessor apparatus 36 converts this electrical signal into a videosignal, and outputs the video signal as an endoscopic image to themonitor 42.

The forceps exit 56 is connected to the forceps entrance 12 of theoperation part 10 via a forceps channel (not shown) provided inside ofthe insertion part 20. A treatment tool such as a forceps which isinserted from the forceps entrance 12 protrudes from the forceps exit56.

The nozzle 58 is provided so as to protrude from the distal end surface26 a of the distal end part 26, and includes a jet port (not shown)facing the observation window 50. An air supply/water supply channel(not shown) provided inside of the insertion part 20 is connected to thenozzle 58. The air supply/water supply channel is connected to the airsupply/water supply apparatus 40 via the air supply/water supplyconnector 34C of the connection part 30. When the air supply/watersupply button 16 provided in the operation part 10 is operated, the gasor the cleaning liquid (cleaning fluid) is selectively fed from the airsupply/water supply apparatus 40 to the endoscope 1 via the airsupply/water supply channel. Then, the gas or the cleaning liquid fedfrom the air supply/water supply apparatus 40 is fed to the nozzle 58via the air supply/water supply channel to be jetted from the jet portof the nozzle 58 toward the observation window 50. This enables cleaningof the observation window 50.

It should be noted that the observation window 50 is cleaned by jettingthe cleaning liquid from the nozzle 58. In this case, liquid drops mayattach onto the observation window 50 after the cleaning. Therefore,after the cleaning, the gas is jetted from the nozzle 58, to therebyremove the liquid drops attaching on the observation window 50.

Incidentally, there is a characteristic that, if the edge part 26 b ofthe outer periphery of the distal end surface 26 a is round-chamfered asin the endoscope 1 of the present embodiment, when the observationwindow 50 is cleaned by the cleaning liquid, the liquid drops attacheasily onto the round-chamfered edge part 26 b. Then, there is a problemthat, if the observation window 50 is placed in the vicinity of the edgepart 26 b as in the endoscope 1 of the present embodiment, in the casewhere the liquid drops attach onto the edge part 26 b in the vicinity ofthe observation window 50, the field of view is blocked by the liquiddrops.

In view of the above, in the endoscope 1 of the present embodiment, thedistal end surface 26 a of the distal end part 26 is configured in thefollowing manner, and thus has a structure in which the liquid drops areless likely to attach onto the observation window 50 and the vicinitythereof (a structure capable of letting the liquid drain off to asatisfactory level).

As illustrated in FIG. 2, an observation window base part 60 is formedon the distal end surface 26 a of the distal end part 26 so as toprotrude from the surrounding area by a prescribed amount, and theobservation window 50 is placed on the observation window base part 60.

The observation window base part 60 has an outer peripheral shape whichis formed into a streamline shape with respect to a flow of the cleaningfluid (the cleaning liquid or the gas) jetted from the nozzle 58, and isconfigured in a manner that: a liquid flow having a low flow rate isprevented from flowing on the observation window 50; a liquid flow whichhas been used for cleaning to promptly can move to the outside of theobservation window 50.

In the endoscope 1 of the present embodiment, as a specific example ofthe streamline shape, the observation window base part 60 is formedsymmetrically to a straight line L which passes through a center O ofthe observation window 50 and is parallel to a flowing direction of thecleaning fluid jetted from the nozzle 58 (a jet direction of thecleaning fluid: a direction indicated by arrows in FIG. 2). Further, anouter shape of a region opposed to the nozzle 58 (a region facing thenozzle 58) is formed into a circle, and an outer shape of a region onthe side opposite to the nozzle 58 (a region not facing the nozzle 58)is formed so as to extend toward the side opposite to the nozzle 58 andconverge at the edge part 26 b of the outer periphery of the distal endsurface 26 a (formed into airfoil section).

In this way, the placement region of the observation window 50 is set tothe base part (observation window base part 60), and the outerperipheral shape thereof is formed into the streamline shape.Accordingly, when the liquid flow is jetted from the nozzle 58, it ispossible to block the liquid flow having a low flow rate at both ends ofthe jet port from flowing on the observation window 50, and to allow theliquid flow to promptly move to the outside of the observation window50. That is, it is possible to let a liquid drain off to a higher level.

It should be noted that, in the endoscope 1 of the present embodiment, aperipheral edge part 60 a of the observation window base part 60 isformed so as to be inclined at a prescribed angle (for example, 45°) asillustrated in FIGS. 3B to 3D, whereby the liquid flow is allowed toflow more smoothly on the observation window 50 and the cleaning liquidwhich has been used for cleaning can be discharged.

In addition, in the endoscope 1 of the present embodiment, asillustrated in FIGS. 4A and 4B, the outer shape of the region on theside opposite to the nozzle 58 is formed so as to extend up to the edgepart 26 b of the outer periphery on the side opposite to the nozzle 58.Then, an end part 60 b at which the outer shape converges isround-chamfered at a prescribed diameter (for example, a diameter ofapproximately 1.0 mm). This makes it possible to reduce a stimulus to abody cavity wall.

It should be noted that, in the endoscope 1 of the present embodiment, around-chamfering diameter (for example, a diameter of 1.0 mm) of theround-chamfered end part 60 b of the observation window base part 60 isformed so as to be smaller than a round-chamfering diameter (forexample, a diameter of 1.6 to 2.0 mm) of the edge part 26 b of the outerperiphery of the distal end surface 26 a. This makes it possible toeffectively prevent the liquid drops from attaching to the vicinity ofthe observation window 50. That is, the liquid drops have thecharacteristic of attaching to a round-chamfered edge part as describedabove, and the liquid drops tend to attach to, particularly, a regionhaving a larger round-chamfering radius among regions which aresimilarly round-chamfered. Therefore, the end part 60 b of theobservation window base part 60 on which the observation window 50 isformed is round-chamfered at a diameter smaller than that of the edgepart 26 b of the outer periphery of the distal end surface 26 a, wherebyit is possible to effectively prevent the liquid drops from attaching tothe vicinity of the observation window 50.

FIG. 3C is a cross-sectional view of the distal end part shown in FIG.3A along the line 3C-3C. As illustrated in FIG. 3C, the peripheral edgepart 60 a of the observation window base part 60 is inclined withrespect to the distal end surface 26 a. In FIG. 3C, the inclinationangle is, for example, 45 degrees, and the edge part 26 b of the outerperiphery of the distal end surface 26 a is round-chamfered with adiameter of, for example, 2.0 mm. FIG. 3D is a cross-sectional view ofthe distal end part shown in FIG. 3A along the line 3D-3D drawn throughthe center of the distal end part and a tip of the end part 60 b. InFIG. 3D, the end part 60 b of the observation window base part 60 isround-chamfered with a diameter of, for example, 1.0 mm. It can beunderstood that, from FIGS. 3C and 3D, the edge part 60 b isround-chamfered with a diameter smaller than that with which the edgepart 26 b of the outer periphery of the distal end surface 26 a isround-chamfered.

As described above, in the endoscope 1 of the present embodiment, theobservation window 50 is formed on the observation window base part 60which protrudes from the surrounding area, and the outer peripheralshape of the observation window base part 60 extends up to the edge part26 b of the outer periphery of the distal end surface 26 a to be formedinto the streamline shape. This makes it possible to effectively preventthe liquid drops from attaching to the observation window 50 and thevicinity thereof. In addition, even in the case where the observationwindow 50 is placed in the vicinity of the edge part 26 b of the outerperiphery of the distal end surface 26 a, it is possible to prevent theliquid drops from attaching to the vicinity of the observation window50, and hence the degree of freedom of a layout of the observationwindow 50 can be increased.

It should be noted that, similarly with regard to the illuminationwindows 52 and 54, if the liquid drops attach thereonto, illuminationperformance and observation performance through the observation window50 are deteriorated. Therefore, in the endoscope 1 of the presentembodiment, the illumination windows 52 and 54 are placed respectivelyon illumination window base parts 62 and 64 which protrude from thesurrounding area by a predetermined amount. The illumination window baseparts 62 and 64 each have an outer peripheral shape which is formed intoa circle corresponding to the outer peripheral shapes of theillumination windows 52 and 54, and peripheral edge parts 62 a and 64 athereof are formed so as to be inclined at a prescribed angle (forexample, 45°). This makes it possible to prevent the liquid flow havinga low flow rate from flowing on the illumination windows 52 and 54.

Second Embodiment

FIG. 5 is a front view illustrating a configuration of a secondembodiment of the distal end surface of the distal end part of theendoscope according to the presently disclosed subject matter.

As illustrated in FIG. 5, the endoscope of the present embodiment isdifferent in the shape of the observation window base part 60 from theendoscope of the first embodiment. Other configuration is the same asthat of the endoscope of the first embodiment, and hence only theconfiguration of the observation window base part 60 is described here.

As illustrated in FIG. 5, the observation window base part 60 of theendoscope of the present embodiment is also formed into a streamlineshape with respect to the flow of the cleaning fluid jetted from thenozzle 58. It should be noted that, in the endoscope of the presentembodiment, the outer shape of the region opposed to the nozzle 58 (theregion facing the nozzle 58) is formed so as to extend toward the nozzle58 and converge toward the center of the jet port of the nozzle 58. Thatis, the outer shape of the region opposed to the nozzle 58 is formed soas to extend and converge toward the nozzle 58.

On the whole, the observation window base part 60 of the endoscope ofthe present embodiment is the same as the observation window base part60 of the endoscope of the first embodiment in that: the observationwindow base part 60 is formed symmetrically to the straight line L (thestraight line which passes through the center O of the observationwindow 50 and is parallel to the flowing direction of the cleaning fluidjetted from the nozzle 58); the outer shape of the region on the sideopposite to the nozzle 58 (the region not facing the nozzle 58) isformed so as to extend toward the side opposite to the nozzle 58 andconverge at the edge part 26 b of the outer periphery of the distal endsurface 26 a; and the peripheral edge part 60 a is formed so as to beinclined at a prescribed angle.

In this way, the outer shape of the region opposed to the nozzle 58 isformed so as to extend toward the nozzle 58 and converge toward thecenter of the jet port of the nozzle 58, whereby it is possible to moreeffectively prevent the liquid flow having a low flow rate from flowingon the observation window 50.

It should be noted that, in the present embodiment, the outer shape ofthe region opposed to the nozzle 58 and the outer shape of the region onthe side opposite to the nozzle 58 are formed symmetrically to eachother, but do not necessarily need to be formed symmetrically to eachother. It is preferable to change as appropriate the shapes thereof inaccordance with a distance to the nozzle 58 and the like.

In addition to the above-mentioned configuration, the outer peripheralshape of the observation window base part may be formed into a rhombicshape and a triangular shape as illustrated in FIGS. 6 and 7,respectively. In this way, the outer peripheral shape of the observationwindow base part is formed so as to converge toward at least the edgepart 26 b of the outer periphery of the distal end surface 26 a, wherebyit is possible to block the liquid flow having a low flow rate fromflowing on the observation window 50, and to allow the cleaning liquidwhich has been used for cleaning to promptly move to the outside of theobservation window 50. In addition, in this case, the converging endpart 60 b is round-chamfered at a diameter smaller than theround-chamfering diameter of the edge part 26 b of the outer peripheryof the distal end surface 26 a, whereby it is possible to prevent theliquid drops from attaching to the edge part 26 b in the vicinity of theobservation window 50.

Third Embodiment

FIG. 8 is a front view illustrating a configuration of a thirdembodiment of the distal end surface of the distal end part of theendoscope according to the presently disclosed subject matter.

As illustrated in FIG. 8, the endoscope of the present embodiment isdifferent in a converging direction of the observation window base part60 from the endoscope of the first embodiment. That is, the observationwindow base part 60 is formed so as to extend toward the edge part 26 blocated at the closest position from the observation window 50, and isformed so as to converge at the edge part 26 b located at the closestposition.

More specifically, the observation window base part 60 is formedsymmetrically to a straight line L1 which connects the center O of theobservation window 50 with a point P located at the closest positionfrom the observation window 50, in the outer peripheral edge of thedistal end surface 26 a (a point whose distance from the outerperipheral part of the observation window 50 is the shortest). An outershape of a region on the center side of the distal end surface 26 a withrespect to a straight line L2 is formed into a circle, and the straightline L2 passes through the center O of the observation window 50, and isorthogonal to the straight line L1. Further, an outer shape of a regionon the outer peripheral side of the distal end surface 26 a with respectto the straight line L2 (the region not facing the nozzle 58) is formedso as to extend toward the outer periphery of the distal end surface 26a and converge at the edge part 26 b of the outer periphery of thedistal end surface 26 a (formed into airfoil section).

The observation window base part 60 of the endoscope of the presentembodiment is the same as the observation window base part 60 of theendoscope of the first embodiment in that: the peripheral edge part 60 ais formed so as to be inclined at a prescribed angle; the converging endpart 60 b is round-chamfered; and the round-chamfering diameter of theround-chamfered end part 60 b is formed at a diameter smaller than theround-chamfering diameter of the similarly round-chamfered edge part 26b of the outer periphery of the distal end surface 26 a.

In this way, the observation window base part 60 is converged toward theedge part 26 b located at the closest position from the observationwindow 50, whereby it is possible to prevent the liquid drops fromattaching to the edge part 26 b in the vicinity of the observationwindow 50.

It should be noted that, although the observation window base part 60 isconverged toward the edge part 26 b located at the closest position inthe present embodiment, it is preferable to adjust as appropriate theconverging direction in accordance with the direction of the nozzle 58(the jet direction of the cleaning fluid), a layout of another element,and the like. That is, it is preferable to converge the observationwindow base part 60 toward a more effective direction in considerationof various factors.

Fourth Embodiment

FIG. 9 is a front view illustrating a configuration of a fourthembodiment of the distal end surface of the distal end part of theendoscope according to the presently disclosed subject matter.

As illustrated in FIG. 9, the endoscope of the present embodiment isdifferent from the endoscope 1 of the first embodiment in that the outerperipheral shapes of the illumination window base parts 62 and 64 arealso formed into a streamline shape.

In this way, the outer peripheral shapes of the illumination window baseparts 62 and 64 are also formed into the streamline shape, whereby it ispossible to prevent the liquid flow having a low flow rate from flowingon the illumination windows 52 and 54, and to promptly eliminate theliquid flow which has flown on the illumination windows 52 and 54 fromthe illumination windows 52 and 54.

In addition, similarly to the observation window base part 60, theillumination window base parts 62 and 64 are formed so as to extendtoward the outer periphery of the distal end surface 26 a, and areformed so as to converge at the edge part 26 b of the outer periphery ofthe distal end surface 26 a. End parts 62 b and 64 b of the illuminationwindow base parts 62 and 64 are round-chamfered at a diameter smallerthan the round-chamfering diameter of the edge part 26 b. Accordingly,it is possible to prevent the liquid drops from attaching to thevicinities of the illumination windows 52 and 54.

It should be noted that, in the present embodiment, although theillumination window base parts 62 and 64 are formed so as to extendtoward respective portions of the edge part 26 b located at the closestpositions from the illumination windows 52 and 54 and converge at therespective portions of the edge part 26 b, the respective convergingdirections thereof are not limited to this embodiment. For example, asillustrated in FIG. 10, the illumination window base parts 62 and 64 maybe formed so as to extend along straight lines L3 and L4 whichrespectively connect the illumination windows 52 and 54 with the nozzle58 and converge at the edge part 26 b of the outer periphery of thedistal end surface 26 a. That is, in consideration of the flow of thecleaning fluid jetted from the nozzle 58, the converging parts of theillumination window base parts 62 and 64 may be formed so as to extendalong the flow thereof.

Fifth Embodiment

FIG. 11 is a front view illustrating a configuration of a fifthembodiment of the distal end surface of the distal end part of theendoscope according to the presently disclosed subject matter.

As illustrated in FIG. 11, in the endoscope of the present embodiment,the observation window base part 60 and the illumination window baseparts 62 and 64 are integrally formed into streamline shapes.

In this way, the observation window base part 60 and the illuminationwindow base parts 62 and 64 may be integrally formed.

It should be noted that, in the embodiment illustrated in FIG. 11, theobservation window base part 60 and the illumination window base parts62 and 64 are formed so as to converge toward respective portions of theedge part 26 b located at the closest position from the observationwindow 50, but the converging directions of the respective base partsare not limited thereto. In addition to the above-mentionedconfiguration, as illustrated in FIG. 12, in consideration of the flowof the cleaning fluid jetted from the nozzle 58, the respective baseparts may be extended along the flow thereof and converged at the edgepart 26 b. That is, it is preferable that the converging directions ofthe observation window base part 60 and the illumination window baseparts 62 and 64 be set to the most effective directions to eliminate theliquid drops in consideration of the flow of the cleaning fluid jettedfrom the nozzle 58, the layout, and the like.

What is claimed is:
 1. An endoscope comprising: an operation part havinga forceps entrance; a distal end part having a flat end surface; anobservation window base part formed on the flat end surface of thedistal end part so as to protrude distally from the flat end surface; anobservation window disposed on the observation window base part; anozzle configured to jet a cleaning fluid toward the observation window;and a forceps exit disposed on the distal end part, a forceps beinginserted through a forceps entrance protruding from the forceps exit,wherein: the observation window base part has a flat surface, and anouter peripheral shape of the observation window base part is inclinedand connects the flat end surface of the distal end part with the flatsurface of the observation window base part; edges of the flat surfaceof the observation window base part decrease in width from theobservation window to a convergence point, the convergence point definesa point in which the edges of the flat surface of the observation windowbase part converge to meet, the convergence point is at least one cornerin a first half of the flat surface of the observation window base partnearer to the nozzle than a second half of the flat surface of theobservation window base part, and a distance from a point at a center ofthe observation window to the convergence point is longer than adistance from the point at the center of the observation window to apoint at which a first straight line connecting the point at the centerof the observation window to a point at a center of the nozzleintersects with an edge of the flat surface of the observation windowbase part; and the observation window, the convergence point, and theforceps exit are located such that a second straight line passing thepoint at the center of the observation window and the convergence pointintersects with the forceps exit.
 2. The endoscope according to claim 1,wherein the operation part includes a suction button for suctioning fromthe forceps exit.